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# basic circuits

### third form electric circuits

Question | Answer |
---|---|

What does p.d. stand for? | Potential Difference |

Units of P.D.? | volts |

Difference between cell and battery? | A battery is a group of cells. |

Letter for P.D. in equations? | V |

What units is current measured in? | amperes or amps (A) |

Letter for current in equations? | I (capital eye!) |

Which kind of circuit has only one path for the electric current? | a series circuit |

Which kind of circuit has more than one track that the current can follow? | a parallel circuit |

What are the units of resistance? | ohms |

What Greek letter is used as a symbol for ohms? | omega |

If the current is 2 A when the p.d. is 6 V, what is the resistance? | 6/2 = 3 ohms |

A 2 ohm resistor and a 3 ohm resistor are connected in series. What is their total resistance? | 5 ohms. |

A 2 ohm resistor and a 3 ohm resistor are connected in series. 4 amps flows through the 3 ohm resistor. What current flows through the other one? | The same, they are in series, 4 amps. |

Three lamps are connected in series to the power supply. One burns out. What happens to the others? | They go out, the circuit is broken. |

Three lamps are connected in parallel to the power supply. One burns out. What happens to the others? | They stay on, they each have their own circuit. |

Name of component that only allows current to flow one way? | diode |

Name of component that only allows current to flow one way and gives out light when current flows? | LED - light emitting diode |

Name of component whose resistance gets smaller when it is hot? | thermistor |

Name of component whose resistance is bigger when it is dark? | LDR, light dependent resistor |

unit of charge? | coulombs |

formula to calculate charge? | current in amps times time in seconds |

A 2 ohm resistor and a 3 ohm resistor are connected in parallel. The PD across the 2 ohm resistor is 8 V. What is the p.d. across the 3 ohm resistor? | The same, they are in parallel, 8 volts. |